Chondroitin sulphate
proteoglycan 4 (CSPG4) is a cell surface
proteoglycan highly expressed by tumour, perivascular and oligodendrocyte cells and known to be involved cell adhesion and migration. This study showed that CSPG4 was present as a
proteoglycan on the cell surface of two
melanoma cell lines, MM200 and Me1007, as well as shed into the
conditioned medium. CSPG4 from the two
melanoma cell lines differed in the amount of
chondroitin sulphate (CS) decoration, as well as the way the
protein core was fragmented. In contrast, the CSPG4 expressed by a colon
carcinoma cell line, WiDr, was predominantly as a
protein core on the cell surface lacking
glycosaminoglycan (GAG) chains. This study demonstrated that CSPG4 immunopurified from the
melanoma cell lines formed a complex with
perlecan synthesized by the same cultured cells. Mechanistic studies showed that CSPG4 bound to
perlecan via hydrophobic
protein-
protein interactions involving multiple sites on
perlecan including the C-terminal region. Furthermore, this study revealed that CSPG4 interacted with
perlecan to support cell adhesion and actin polymerization. Together these data suggest a novel mechanism by which CSPG4 expressing cells might attach to
perlecan-rich matrices so as those found in connective tissues and basement membranes.